DESCRIPTION: (modified from that provided by applicant) The goals of the proposed K01 project are to investigate the neurophysiological mechanisms by which the comorbidity of substance use disorders and dissociation increases the risk for development of posttraumatic stress disorder (PTSD) in a female sample of acute trauma victims. The sample will be comprised of 128 women who were raped or physically assaulted as identified through police and victim assistance agencies. A prospective design will be used to assess these women at one month posttrauma on a battery of self-report measures of symptoms and cognitions. The Diagnostic Interview Schedule (DIS) will be used to assess substance use disorders and severity. In addition, a Stress Induced Analgesia (SIA) paradigm, using the cold pressor pain test, will be used to obtain a physiological index of dissociation. The index will be used as a gold standard against which subjects with substance use disorders and no substance use disorders will be stratified. At three months posttrauma, these groups will be assessed for posttraumatic stress disorder using the DIS. Further, neurophysiological indices (Event Related Potentials) of information processing (P300's) will be used to objectively examine the role of comorbid substance use disorders and dissociation as risk factors for the development of PTSD. This study will build upon a highly successful recruitment plan already being used by the candidate. This award would also allow this young investigator to further the goals of a recently funded NIDA B/START grant, which provided pilot data for investigating the role of substance use and dissociation as risk factors for the development of PTSD. Conducting the proposed study with a larger sample and biological indices will have important implications in objectively identifying the etiological factors that underlie this relationship.